1.) 是用javamail包；

2) 在發件人郵箱的設定中開啟POP3/SMTP/IMAP

import java.util.Properties;

import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class sendMail {
	public static boolean sendMail(String to, String code) {  
		try {  
	        Properties props = new Properties();  
	        props.put("username", "username");  // 使用者名稱
	        props.put("password", "password");  // 登陸密碼 
	        props.put("mail.transport.protocol", "smtp" );  
	        props.put("mail.smtp.host", "smtp.163.com");  
	        props.put("mail.smtp.port", "25" );  
	
	        Session mailSession = Session.getDefaultInstance(props);  
	
	        Message msg = new MimeMessage(mailSession);     
	        msg.setFrom(new InternetAddress("
 
[email protected]")); // 發件人郵件
	        msg.addRecipients(Message.RecipientType.TO, InternetAddress.parse(to));   
	        msg.setSubject("啟用郵件");   
	        msg.setContent("<h1>此郵件為測試郵件</h1>","text/html;charset=UTF-8"); // 傳送正文內容
	        msg.saveChanges();  
	
	        Transport transport = mailSession.getTransport("smtp");
	        System.out.println("---------");
	        transport.connect(props.getProperty("mail.smtp.host"), props  
	                .getProperty("username"), props.getProperty("password"));   
	        transport.sendMessage(msg, msg.getAllRecipients());  
	        transport.close(); 
	        System.out.println("==============");
	    } catch (Exception e) {  
	        e.printStackTrace();  
	        System.out.println(e);  
	        return false;  
	    }  
	    return true;  
	}
	public static void main(String[] args) {
	    sendMail("
 
[email protected]", "101");   // 收件人郵件
	}
}